Telephone system



Aug. 11, 1936.

J. B. MCKIM 2,050,722 I TELEPHONE SYSTEM Filed March 20, 1935 2 Sheets-Sheet 1 INVE/V TOR J 8. Mc K M ATTORNEY 6- J. B. MCKIM 2,050,722

TELEPHONE SYSTEM Filed March 20, 1955 2 Sheets-Sheet 2 M/VE/VTOA J. B. McK/M A TTOR/VEV CAD Patented Aug. 1936 a j I 2,050,722

TELEPHONE SYSTEM James B. McKim, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application March 20,

Claims.

This invention relates to automatic or semiautomatic telephone systems and more particularly to repeaters for use therein.

In multi-office exchange areas it is often necessary to employ long inter-oflice trunks to interconnect the more widely separated ofiices. Consequently such trunks must be equipped with repeaters to improve the voice current transmission and to enable the transmission of impulses dialed at the originating oflice for setting selector switches in the terminating office. When dialed impulses are transmitted through repeaters there is a distinct tendency for the repeated impulses to become distorted to such an extent that they are not fully suitable for controlling the accurate setting of selector switches. To obviate this difiiculty repeaters have been proposed heretofore for introducing a correction in the character and speed of the retransmitted impulses.

The present invention has for its object the improvement of the impulse correcting repeaters heretofore proposed in that the outgoing impulses may be transmitted at a predetermined constant speed commensurate with the speed at which selector switches are accurately responsive and with a fixed percentage of break period to make period regardless of the speed and percentage of break period to make period of the dialed or incoming impulses.

In accordance with the present invention, the improved repeater functions much in the manner of a register sender in that the incoming impulses are stored and outgoing impulses are transmitted in accordance with the stored impulses. For storing the incoming impulses a single register switch of the rotary step-by-step type is employed which advances a number of steps for each dialed impulse series commensurate with the numerical value of the digit in such a manner that the impulse series are additively stored therein. A small condenser is connected to each terminal of certain banks of the switch and provision is made for placing a positive charge on such ones of the condensers as are connected to the bank terminals of the register upon which a brush of the register comes to rest at the termination of each successive incoming impulse series. Such condensers as thus become charged in response to the dialing of series of impulses serve as markers to indicate the numerical value of each incoming impulse series.

For generating impulses for retransmission, a condenser timed relay is provided, the operating and releasing time of which can be very accurately determined. This relay in turn controls 1935, Serial No. 11,927

the operation and release of a pair of relays, one of which controls the making and breaking of the outpulsing circuit and the other of which controls the stepping of a second register or impulse counting switch of the rotary step-by-step type. The condensers are also connected respectively to terminals of certain of the banks of the counting switch and the. brushes which cooperate with these terminals are connected to the control electrode of a gas-filled tube. Under the control of the impulse generating and transmitting relays the counting switch is advanced during the transmission of the first series of outgoing impulses until a. terminal is reached which is associated with the first charged marking condenser at which time as many outgoing impulses will have been transmitted as were recorded on the first switch in response to the first digit dialed. The first charged condenser is now connected to the control electrode of the tube and the normal biasing potential on the control electrode is now made more positive whereby the tube immediately flashes to operate a. relay to arrest the further generation and transmission of impulses. Through the operation of relay means the reoperation of the timed relay and the impulse transmitting relays is delayed to measure'off a predetermined period before the transmission of the next series of outgoing impulses and to deionize the tube. Upon the termination of the delay interval the timed relay and impulse transmitting relays again function to transmita second series of impulses over the outpulsing path and to further advance the counting switch until it reaches a terminal which is associated with the second charged marking condenser at which time as many outgoing impulses will have been transmitted as were recorded on the first switch in response to the second digit dialed. The tube again flashes to terminate the transmission of the second series of impulses. In this manner as many series of impulses-are transmitted as were. registered upon the first register.

Since the operating and releasing time of the timed relay may be very accurately determined, the speed at which impulses are transmitted over the outpulsing circuit and the percentage of break period to make period thereof may be very accurately adjusted.

For a clearer understandingof the invention, reference may be had to the following detailed description taken in connection with the accompanying drawings in which:

Fig. 1 shows a subscribers line, the schematic representation of a'line finder and a first selector switch, and an outgoing trunk circuit to which the selector switch has access, equipped with a voice current repeating coil and a dial impulse repeater; and

Fig. 2 shows an impulse storage and counting circuit which functions with the impulse repeater of Fig. 1.

The digit registering switch 200 and the impulse counting switch 250 of Fig. 2 are of the well-known rotary step-by-step type having no normal position and each being provided with six brushes and associated arcuate terminal banks and a stepping magnet. The banks and brushes of each switch are arranged in pairs, brushes 20! and 202, 203 and 204, 205 and 206 of switch 260 being thus paired and brushes 253 and 254, 255 and 256 of switch 250 being also so paired. In this connection it is to be noted that the brushes constituting each such pair are positioned on the driving shaft 180 apart so that one brush, for example 202, enters its bank of associated terminals one step after its paired brush 20I leaves the last terminal of its bank. The line finder I05 and selector switch I02, schematically illustrated in Fig. 1, may be of the well-known construction employed generally in dial systems of the step-by-step type.

The tube illustrated at I20 is of the gaseous discharge type filled with a low pressure gaseous content, which may be neon, argon, helium, mercury vapor or combinations of gases of this group. The tube has a certain characteristic, namely, that the gaseous content will become ionized and thus conducting on one potential determined by the electrode design, the nature of the gaseous content and its pressure, but once rendered conducting will maintain this condition of conductivity on a much lower potential. The tube may be of the hot cathode type, as disclosed, having a cathode heated conductively from a filament illuminated by a source of direct current, or the filament may itself serve as the cathode or be illuminated by a source of alternating current. A tube of the coldcathode type might also be employed.

It will be assumed that at the time the subscriber at substation I00 initiates a call by removing his receiver. from the switchhook that switches 200 and 250 are resting with their brushes in the position indicated and that relay I03 is normally operated over the circuit extending from ground through its winding, conductor I04, brush 205, conductor 208, brush 255, conductor I05, winding of relay I06, to battery. Relay I06 is not operated over this circuit. In response to the initiation of the call, the calling line is extended in the well-known manner through the operation of line finder IOI to the first selector switch I02. It will further be assumed that the calling subscriber desiring a connection with a subscribers line located in a distant ofiice dials the directory number of such line which, for the purposes of illustration, may be Main 9913.

In response to the dialing of the ofiice code letter M, which has the numerical equivalent of 6, the brushes of the first selector I02 are stepped to a position opposite the sixth bank level and are then rotated over this level to hunt for an idle trunk. It will be assumed that the trunk disclosed in Fig. 1 is idle and that the brushes of selector I02 come to rest upon the terminals of this trunk. The dialing loop is now extended from battery through the upper winding of relay I01, upper normal contacts of relay I08, lower left winding of repeating coil I09, ring brushes H0 and III of selector I02 and line finder IOI over the calling subscribers line, tip brushes I I2 and I I3 of line finder ml and selector I02, upper left winding of repeating coil I09, lower normal contacts of relay I08, to ground through the lower winding of relay I0I.

Relay I01 operates establishing a circuit which extends from ground at its front contact serially through the windings of slow-to-operate relay I I4 and slow-to-release relay I I5 to battery. Relays H4 and II5 both operate and establish an operating circuit for relay I I6 extending from battery through the winding of relay II6, upper front contact of relay II4, to ground at the upper front contact of relay II5. Relay II6 operates and locks in a circuit from battery through its winding and upper front contact to ground at the upper front contact of relay I I5 independent of the continued operation of relay II4. Relay II5 upon operating connects ground over its outer lower front contact in shunt of the winding of relay I03 thereby causing the release of relay I03 and the operation of slow-to-release relay I06; prepares the operating circuit of stepping magnet 26! of switch 200 over its inner upper front contact and, at its inner lower front contact, connects the positive or grounded terminal battery to the anode of tube I20 over a circuit extending through the winding of the anode ilelay III, the inner lower back contact of relay The filament of tube I20 is heated in a circuit from battery through rheostat I I9 and resistance I2I and the grid is normally negatively biased in a circuit from the negative terminal of battery through resistance I22 so that tube I20 will not ionize. However, should either brush 253 or 254 of switch 250 be in engagement with a bank terminal to which a positively charged condenser, such as 2 I8 or 2 I 6 is connected, positive potential will be applied from such condenser over brush 253 or brush 254, conductor I36 to the grid of tube I20 thereby causing the tube to ionize and operate the anode relay II'I.

With relay II6 operated a circuit is established from ground over the lower contact thereof through resistance I23, winding and normal contacts of relay I24 to battery over the back contact of relay I25 and in parallel over the front contact of relay I06 to battery through the winding of relay IIB. Relays I24 and H8 both operate, relay I24 locking in a circuit from ground at the lower contact of relay I I6, through resistance I23, winding and lower alternate contacts of relay I24, to battery, and closing the outgoing loop from conductor I26, upper right winding of repeating coil I09, winding of supervisory relay I2'I, lower right winding of repeating coil I09, upper contacts of relay I24 to conductor I28. Relay II8 upon operating opens the cathodeanode circuit previously traced through the winding of anode relay I I! at its inner lower back contact, opens the operating circuit of the pulse generating relay I 25 at its lower back contact and at its upper back contact opens the outpulsing circuit which extends from conductor I26 over the upper back contact of relay I I8 and the upper front contact of relay I24 to conductor I28. The circuits are now ready to receive incoming impulses resulting from the operation of the substation dial for the first numerical digit 9 of the desired line number.

in response to the operation of the dial for the second dialed digit 9, relay.I0I releases nine times and upon each release closes the operating circuit for stepping magnet 20? of switch 200 which may be traced from ground'at the back contact of relay I01, inner upper front contact of relay H5, conductor I29, to battery through the winding of magnet 201. Upon the first" release of relay I01 the operating circuit for relays H4 and H5 is opened and relay H4 releases but relay II5 being sloW-to-release remains operated over the short intervals that relay I01 is deenergized during its response to the series of impulses and holds relay H6 operated. Relay H0 beingslow-to-oper-ate does not operate again until relay I01 remains steadily energized at the end of the dialed impulse series. In response to the nine impulses transmitted through stepping magnet 201 the magnet steps the brushes of switch 200 forward nine steps.

As brush 20! encounters the successive terminals of its are it causes the successive discharge of the condensersconnected to such terminals, condenser 209 becoming discharged in a circuit extending from the negative terminal of grounded battery over brush 20 I, through condenser 209 to the negative terminal of grounded battery when brush 20I encounters the twelfth terminal of its arc and condenser 2I0 becoming discharged when brush 20I encounters the thirteenth terminal of its arc. When relay I01 reenergizes following the completion of the dialing of the second digit 9, relay II l reoperates and a charging path for condenser 209 is extended from ground at the inner contact of relay H4, conductor I30, brush 203, the thirteenth terminal of its arc, condenser 209 to the negative terminal of grounded battery. Condenser 209 therefore becomes positively charged with respect to negative battery.

In response to dialing the next digit assumed to be 9, relay I01 transmits nine stepping impulses to magnet 20'! to advance the brushes of switch 200 nine further steps and, upon its first release in response to the first dialed impulse, causing the release of relay H4. As brush 29I encounters successive terminals of its are it causes the successive discharge of the condensers connected to such terminals, condenser 2H becoming discharged when brush 20! encounters the twenty-first terminal of its arc and condenser 2I2 becoming discharged when brush 20I encounters the twenty-second terminal of its arc. When relay I01 reenergizes following the completion of the dialing of the third digit 9, relay H0 reoperates and a charging path for condenser 2H is established from ground at the inner contact of relay H4, conductor I30, brush 203, the twenty-second terminal of its arc, condenser 2II to the negative terminal of grounded battery. Condenser 2H therefore becomes positively charged with respect to negative battery.

In response to dialing the next digit, assumed to be 1, relay I07 transmits a single stepping impulse to magnet 201 to advance the brushes of switch 200 one step further. Relay H4 also releases as before described. Brushes 20I, 203 and 205 are now advanced out of engagement with terminals of their arcs and brushes 202, 200 and 209 are advanced into engagement with the first terminals of their arcs, the engagement of brush 202 with the first terminal of its arc establishing a discharge path for condenser 2I3 extending from the negative terminal of grounded battery over brush 202 through condenser '2I3 to the negative terminal of grounded battery. When relay I01 reenergizes following the completion of the dialing of the fourth digit 1, relay II I reoperates and a charging path for condenser 2I2 is established from ground at the inner contact of relay II l, conductor I30, brush 204 and the first terminal of its arc, condenser 2I2 to the negative terminal of grounded battery. Condenser 2I2 is thus positively charged with respect to negative battery.

In response to the dialing of the last digit, assumed to be 3, relay I01 transmits three impulses to the stepping magnet 201 to advance the brushes of switch 200 three further steps. Relay H4 also releases as before described. As brush 202 encounters the second, third. and fourth terminals of its arc, discharge paths are established thereover as previously described for condensers 2M, 2I5 and 2I0. When relay I0I reenergizes following the completion of the dialing of the fifth and last digit 3, relay II l reoperates and a charging circuit is established for condenser 2I5 from ground at the inner. contact of relay H4, conductor I30, brush 204 and the fourth terminal of its arc, condenser M5 to the negative terminal of grounded battery. Condenser 2I5 is thus positively charged with respect to negative battery.

It is thus to be noted that switch 200, in advancing from its norm-a1 resting position to the position in which it stops upon the termination of the last dialed impulse series, has caused the successive discharge of all condensers connected to terminals with which brushes 20I and 202 engage, and has caused'the recharging of the condensers connected to terminals upon which brushes 203 and 204 were stopped at the ter-- mination of each successive impulse series. Thus following the complete dialing of the desired line number condensers 209, 2| I, 2I2 and 2I5 remain positively charged to mark terminal positions in which brushes 203 and 204 stopped to register the successively dialed digits 9913.

At the time switch 200 took its first step to register the second dialed digit 9, the circuit previously traced through the winding of relay I06 is opened by the advance of brush 205 and relay I 06 releases followed by the release of relay H8 as determined by their slow releasing characteristics. Relay H8 upon releasing reconnects positive anode potential to the anode of tube I20 through the winding of relay H1 and, with relay I06 released, establishes an operating circuit for pulse generating relay I25. This circuit may be traced from ground over the lower contact of relay H6, back contact of relay I05, lower back contact of relay H8, lower winding of relay I to battery and, in parallel therewith, through the upper winding of relay I25 and condenser I3I to battery. Relay I25 is diiferentially wound and the windings are so related that upon the establishment of the previously traced circuits therethrough the upper winding overbalances the lower winding and the armature of the relay is thereby held against its back contact. 'As the condenser I3I becomes charged, the current flowing through the upper winding gradually diminishes until the lower winding overbalances the upper winding and the armature of the relay is moved to make its front contact. Thereupon a discharge path is established for condenser I3! from the negative terminal of grounded battery through condenser I3I, resistance I32, front contact of relay I25 to the negative terminal of grounded battery. After an interval determined by the value of resistance I32, condenser I 3| becomes fully discharged and the upper winding of relay I25 becomes energized in a circuit from ground at the lower front contact of relay II6 over the back contacts of relays I06 and H8, upper winding of relay I25, resistance I32, front contact of relay I25 to battery. The upper winding of relay I25 now overbalances the lower winding and the armature of relay I25 is moved to make its back contact. This cycle of operations is repeated so long as relays I06 and H8 remain deenergized, relay I25 thus operating and releasing at a rate of twenty cycles per second.

On the first movement of the armature of relay I25 from its back contact to its front contact a shunt around the winding of relay I33 is opened. This shunt may be traced from battery over the back contact of relay I25, back contact of relay I 33, back contact of relay II1, winding of relay I33, lower alternate contacts of relay I24 to battery. With this shunt opened, relay I 33 now operates in a circuit extending from battery, lower alternate contacts'of relay I24, winding of relay I33, upper back contact of relay I I1, resistance I34 to ground at the lower front contact of relay II6. When relay I25 next moves its armature to its back contact, the winding of relay I24 is shunted over a path extending from battery, lower alternate contacts and winding of relay I24, lower front contact of relay I33, back contact of relay I25 to battery, relay I33 being held operated after the release of relay I24 over a circuit extending from battery, back contact of relay I25, lower normal contacts of relay I24, winding of relay I33, back contact of relay II1, resistance I34 and thence to ground at the lower contact of relay I I6. On the next movement of the armature of relay I25 to its front contact this holding circuit of relay I33 is opened and relay I33 releases. As relay I25 continues to vibrate its armature relays I24 and I33 repeatedly operate and release in the sequence above described with the result that relay I24 makes and breaks the previously traced outpulsing loop over conductors I 26 and I 28 at the rate of ten cycles per second.

On each energization of relay I33, a circuit is established from ground at its upper contact over conductor I35, winding of stepping magnet 251 of switch 250 to battery and thus upon each operation and release of relay I33 magnet 251 advances the brushes of switch 250 one step. Each step of switch 250 corresponds to the transmission of one impulse over the outgoing pulsing loop under the control of relay I24.

On the ninth operation of relay I33 and the following cyclic release of relays I24 and I33 nine impulses will have been transmitted to the outpulsing loop and the brushes of switch 250 will have been advanced nine steps with brush 253 in engagement with the thirteenth terminal of its arc to which the positively charged condenser 209 is connected. 'Ihereupon a circuit is established from the negative terminal of grounded battery through condenser 209, over brush 253, conductor I36 to the grid of tube I20. The positive charge on condenser 209 thus applied to the grid of tube I20 overcomes the normal negative bias thereon to such an extent that the tube ionizes and operates the anode relay II1 over its cathode-anode circuit. This circuit may be traced from the negative terminal of grounded battery, through resistance I31, cathodeand anode of tube I20, inner lower back contact of relay I I8, winding of relay II1 to ground at the inner lower front contact of relay II5.

Relay III upon operating opens the operating circuit of relay I33 at its back contact to prevent the transmission of further stepping impulses to the stepping magnet 251, thereby arresting switch 250 with its brushes in engagement with the thirteenth terminals of their arcs. Relay I I1 also closes at its lower contact an obvious circuit for relay I06 which upon operating opens at its back contact the operating circuit for the impulse generating relay I25 and at its front contact establishes the operating circuit of relay I I8. The operating circuit of relay I25 is opened at the time relay I25 has its armature in engagement with its back contact and therefore the previously traced operating circuit for relay I24 is established, relay I 24 then operating, locking and maintaining the outgoing loop closed at its upper front contact.

Relay II8 upon operating opens the operating circuit of relay I25 at a second point and opens the cathode-anode path through tube I20. Tube I20 now deionizes releasing relay II1. Relay II1 upon releasing opens the circuit of relay I06 which, in turn, opens the circuit of relay II8. Relays I06 and H8 are made slow-to-release for the purpose of interposing a suitable delay interval to permit a trunk hunting operation of the selector switch operated by the preceding train of impulses transmitted over the outpulsing loop before the operating circuit of relay I25 is reestablished to start impulsing for the next digit series. Relay II1 upon releasing also prepares the operating circuit of relay I33.

When relays I06 and H8 finally both release relay I25 again functions to cyclically operate and release relays I24 and I33 in the manner previously described to transmit a further series of impulses over the outpulsing loop and to further advance the brushes of switch 250.

It was assumed that the second digit, registered by the advance of switch 200, was the digit 9 and that in response thereto condenser 2 was positively charged. When, therefore, the brushes of switch 250 are further advanced nine steps or to the twenty-second terminals of their arcs a circuit is established from the negative terminal of grounded battery through condenser 2 over brush 253, conductor I36, to the grid of tube I20. In the manner previously described tube I20 ionizes operating relay II1. Relays I24, I33, I06, I I8 and I25 now function as previously described to terminate the transmission of further impulses over the outpulsing loop and to the stepping magnet 251 of switch 250 and to prepare the circuits for the transmission of the next train of impulses.

The next digit, registered by the advance of switch 200, was the digit 1 as indicated by the positively charged condition of condenser 2I2. When, therefore, the brushes of switch 250 are subsequently advanced one further step during the transmission of the next train of impulses under the control of relays I25, I24, and I33, brushes 253 and 255 are moved out of engagement with their terminal arcs and brushes 254 and 256 are moved into engagement with the first terminals of their respective arcs. A circuit is now established from the negative terminal of grounded battery through condenser 2I2, over brush 254, conductor I36 to the grid of tube I 20. In the manner previously described tube I20 ionizes operating relay I,I1. Relays I24, I33, I06, H8 and I25 now function as previously described to terminate the transmission of further impulses over the outpulsing loop and to the stepping magnet 251 of switch 250 and to prepare the circuits for the transmission of the next train of impulses.

The next digit, registered by the advance of switch 200, was the digit 3 as indicated by the positively charged condenser 2I5. When, therefore, the brushes of switch 250 are subsequently advanced three further steps during the transmission of the next train of impulses under the control of relays I25, I24 and I33, brushes 254 and 256 will engage the fourth terminals of their respective arcs. A circuit is now established from the negative terminal of grounded battery through condenser 2I5 over brush 254, conductor I36, to the grid of tube I20. In the manner previously described tube I 20 ionizes operating relay II'I. Relays I24, I33, I05, H8 and I25 now function as previously described to terminate the transmission of further impulses over the outpulsing loop and to the stepping magnet 257 of switch 250, and to prepare the circuits for the transmission of the next train of impulses.

Since at this time trains of impulses corresponding to all of the dialed series of impulses registered by the advance of switch 200 have been transmitted, switch 250 will have advanced its brushes 254 and 250 to the fourth terminals of their respective arcs and as it will be recalled that brushes 204 and 206 of switch 200 were arrested on the fourth terminals of their respective arcs at the termination of dialing, a circuit is established from ground at the lower front contact of relay II 5, conductor I04, brush 200 and the fourth terminal of its arc, conductor ZII, the fourth terminal of the arc with which brush 250 is engaged, brush 25B, conductor I05, winding of relay I00, to battery. Thus relay I06 is held operated at the termination of the transmission of the preceding impulse series, in turn holding relay I I8 operated and therefore impulse generating relay I25 and relays I24 and I33 cannot function to transmit additional impulses. Relay I24 is, however, locked operated over its lower alternate contacts to ground at the lower contact of relay H6 to maintain the talking circuit closed over the outgoing trunk conductors I26 and I28 through the right windings of repeating coil I09 and the winding of polarized supervisory relay I2I.

When the'called subscriber responds, relay I21 operates in turn operating the reversing relay I08 which transposes the connection of battery and ground through the windings of relay I0I for supervisory purposes. When the conversation over the circuit established from the'calling line and trunk conductors I20 and I28 is terminated and the calling subscriber restores his receiver to the switchhook, relay I01 releases in turn causing the release of relays H4, H5 and I I0. Relay I I0 upon releasing opens the circuits of relays I I8 and I24 and these relays also release. Relay II5 upon releasing opens the shunt around the winding of relay I03 and relay I03 now operates in a circuit extending from ground through its winding over conductor I04, brush 200, conductor 2 II, brush 256, conductor I05 to battery through the winding of relay I00. Relay I05 does not remain operated over this circuit due to the high resistance of the winding of relay I03 and therefore releases.

Relay I24 upon releasing opens the outgoing trunk loop thereby initiating the release of other selector switches employed in the establishment of the connection, the connector switch being retion of digits by-the advancement of switch 200,.

but before all trains of impulses have been transmitted over the outpulsing loop in accordance therewith, relays I0'I, II4,'II5,and H0 will be released, in turn causing the release of relays I24, I33, H8 and I24 if any of these relays are at the time operated. Since switch 250 has not advanced either its brush 255 or its brush 256 to a position corresponding to that of brush 205 or 206 of switch 200, no circuit will be eiTective for relays I03 and I06 and these relays will also release. With both relays H5 and I03 released an interrupted stepping circuit will be closed for magnet 25? of switch 250 extending from ground over the lower back contact of relay II5, back contact of relay I03, conductor I30, interrupter contacts and winding of magnet 25? to battery. Magnet 25'I will thereupon advance the brushes of switch 250 until either brush 255 or brush 256 engages a terminal connected to a terminal upon which brush 205 or 'brush'206 of switch 200 is resting whereupon relay I03 will operate in a circuit over conductor I04, brush 205 or 206, a loop conductor such as 208 or 2H, brush 255 or 255, conductor I05, winding of relay I00 to battery. Relay I00 does not operate over this circuit but relay I03 upon operating will open the circuit of magnet 25'I thereby arresting the brushes of switch 250 in a position corresponding to the position of the brushes of switch 200.

If at any time either switch 200 or 250 is advanced accidentally so that their brushes do not occupy corresponding positions, relay I03 willrelease and switch 250 will be advanced in the manner just described until the brushes of switch 250 are positioned on terminals of their arcs which correspond to the terminals of the arcs with which the brushes of switch 200 are at the time in engagement.

What is claimed is:

1. In a telephone system, a repeater comprising a register switch for successively and additively registering the plurality of series of incoming impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series of impulses, and means controlled by said impulse transmitter during the transmission of each outgoing series of impulses for advancing said counting switch to a position corresponding to the position to which said register switch was set for registering the corresponding incoming series of impulses.

2. In a telephone system, a repeater comprising a register switch for successively and additively registering the plurality of series of incoming impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series of impulses, means controlled by said impulse transmitter for operating said counting switch to successively and additively register therein said series of outgoing impulses, and means for terminating the I of incoming'impulses r controlled by said charged condenser to terminate said series of outgoing impulses when said counting switch is advanced to aterminalthereof to' which said charged condenser is connected.

4. In a telephone system, a repeater 'comprising a register switch for registering a series of incoming impulses, an impulse transmitter'for generating and transmitting a series of outgoing impulses, a counting switch for counting a series of outgoing impulses, means controlled by said impulse transmitter for operatingrsaid counting switch, condensers connected to corresponding bank terminals of said switches, means operative upon the termination of'an incoming series of impulses to place a charge on one of said condensers to mark the position to which said register switch was set in response thereto, and means including a gas-filled tube controlled by said charged condenser to terminate said series of outgoing impulses when said counting switch is advanced to a terminal thereof to which said charged condenser is connected. v

5. In a telephone system, a repeater comprising a register switch for registering a series of incoming impulses, an impulse transmitter for generating and transmitting a series of outgoing impulses, a counting switch for counting a series of outgoing impulses, means controlled by said impulse transmitter for operating said counting switch, condensers connected to corresponding bank terminals of said switches, means operative upon the termination'of anincoming series of impulses to place a positive charge on one of said condensers to mark the position to which said register switch was set in response thereto, a gas-filled tube having its control electrode normally negatively biased to a potential below the ionization potential of said tube, a relay in the cathode-anode circuit of said tube, and means operative when said counting switch is advanced to a terminal thereof to which said charged condenser is connected to change'the potential on said control electrode to cause said tube to ionize and operate said relay thereby terminating the operation of said impulse transmitter.

6. In a telephone system, a repeater comprising a register'switch for successively and additively registering the plurality of series of incoming impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series of impulses, means controlled by said impulse transmitter for operating said counting switch, condensers connected to bank terminals of said switches, means operative'upon the terf transmission of each series of outgoing impulses- 1 when said counting switch reaches a position c orresponding to the position'towhich said registerswitch was set to register thecorresponding series mination of each incoming series of impulses to place a charge on the condenser which is connected to a terminal to which said register switch is advanced in response to such series of impulses, and means controlled by said condenser to terminate said series of outgoing impulses when said counting switch is advanced to terminals to which charged condensers are connected.

'7. In a telephone system, a repeater comprising a register switch for successively and additively registering the plurality of series of incoming impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series, means controlled by said impulse transmitter for operating said counting switch, condensers connected to bank terminals of said switches, means operative upon the termination of each incoming series of impulses to place a charge on the condenser which is connected to a terminal to.

which said register switch is advanced in response to such series of impulses, and means including a gas-filled tube controlled successively by said charged condensers to terminate said series of outgoing impulses when said counting switch is advanced to terminals thereof to which said charged condensers are connected.

8. In a telephone system, a repeater comprising a register switch for successively and additively registering the plurality of series of incoming impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series of impulses, means controlled by said impulse transmitter for operating said counting switch to successively and additively register therein said series of outgoing impulses, condensers connected to bank terminals of said switches, means operative upon the termination of each incoming series of impulses to place a charge on the condenser which is connected to a terminal to which said to which said register switch was set to register the corresponding series of incoming impulses;

9. In' a telephone system, a repeater comprising a register switch for successively and additively registering the plurality of series of impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series of impulses, means controlled by said impulse transmitter for operating said counting switch to successively and additively register therein said series of outgoing impulses, condensers connected to bank terminals of said switches, means operative upon the termination of each incoming series of impulses to place a charge on the condenser which is connected to a terminal to which said register switch is advanced in response to such series of impulses, 'a gas-filled tube havingits control electrode normally negatively biased to a potential below the ionization potential of said tube, a relay in the cathode-anode circuit of said tube, and means operative each time said counting switch is advanced to a terminal thereof to which a charged condenser is connected'to change the potential on said control'electrode to cause said tube to ionize and operate saidre lay thereby momentarily terminating the operation of said impulse transmitter.

10. In a telephone system, a repeater comprising a register switch for successively and additively registering the plurality of series of incoming impulses of a call designation, an impulse transmitter for generating and transmitting series of outgoing impulses, a counting switch for counting the impulses of each outgoing series of impulses, means controlled by said impulse transmitter for operating said counting switch to successively and additively register therein said series of outgoing impulses, a gas-filled tube, a relay for arresting the operation of said transmitting means, means for causing said tube to ionize and operate said relay each time said counting switch reaches a position corresponding to any position to which said register switch was set, and means for measuring a delay interval following each ionization of said tube, for thereafter deionizing said tube and for restarting said impulse transmitter.

JAMES B. McKIM. 

